The present invention relates to a low sulfur, low ash, low phosphorous lubricant composition and method for lubricating an internal combustion engine, providing improved fuel economy and retention of fuel economy and wear and friction reduction.
Fuel economy is of great importance, and lubricants which can foster improved fuel economy by, for instance, reducing friction within an engine, are of significant value. The present invention provides a low sulfur, low ash, low phosphorous lubricant composition, including an additive package, which leads to improved fuel economy in an internal combustion engine. This improvement is effected by providing an additive package in which the friction modifier component is exclusively or predominantly a tartrimide or a tartramide or combinations thereof.
U.S. Pat. No. 4,237,022, Barrer, Dec. 2, 1980, discloses tartrimides useful as additives in lubricants and fuels for effective reduction in squeal and friction as well as improvement in fuel economy.
U.S. Pat. No. 4,952,328, Davis et al., Aug. 28, 1990, discloses lubricating oil compositions for internal combustion engines, comprising (A) oil of lubricating viscosity, (B) a carboxylic derivative produced by reacting a succinic acylating agent with certain amines, and (C) a basic alkali metal salt of sulfonic or carboxylic acid. An illustrative lubricant composition (Lubricant III) includes base oil including viscosity index modifier; a basic magnesium alkylated benzene sulfonate; an overbased sodium alkylbenzene sulfonate; a basic calcium alkylated benzene sulfonate; succinimide dispersant; and zinc salts of a phosphorodithioic acids.
U.S. Pat. No. 4,326,972, Chamberlin, Apr. 27, 1982, discloses lubricant compositions for improving fuel economy of internal combustion engines. The composition includes a specific sulfurized composition (based on an ester of a carboxylic acid) and a basic alkali metal sulfonate. Additional ingredients may include at least one oil-dispersible detergent or dispersant, a viscosity improving agent, and a specific salt of a phosphorus acid.